Magnetic field and convection in the cool supergiant Betelgeuse
We present the outcome of a highly-sensitive search for magnetic fields on the cool supergiant Betelgeuse. A time-series of six circularly-polarized spectra was obtained using the NARVAL spectropolarimeter at Télescope Bernard Lyot (Pic du Midi Observatory), between 2010 March and April. Zeeman sign...
| Main Authors: | , , , , , , |
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| Format: | Text |
| Language: | unknown |
| Published: |
arXiv
2011
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| Subjects: | |
| Online Access: | https://dx.doi.org/10.48550/arxiv.1109.3979 https://arxiv.org/abs/1109.3979 |
| Summary: | We present the outcome of a highly-sensitive search for magnetic fields on the cool supergiant Betelgeuse. A time-series of six circularly-polarized spectra was obtained using the NARVAL spectropolarimeter at Télescope Bernard Lyot (Pic du Midi Observatory), between 2010 March and April. Zeeman signatures were repeatedly detected in cross-correlation profiles, corresponding to a longitudinal component of about 1 G. The time-series unveils a smooth increase of the longitudinal field from 0.5 to 1.5 G, correlated with radial velocity fluctuations. We observe a strong asymmetry of Stokes V signatures, also varying in correlation with the radial velocity. The Stokes V line profiles are red-shifted by about 9 km/s with respect to the Stokes I profiles, suggesting that the observed magnetic elements may be concentrated in the sinking components of the convective flows. : Submitted to Lecture Notes in Physics (CNRS astronomy school : "From solar environment to stellar environment") |
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